9Cr-2W creep strength enhanced ferritic steel for ultra supercritical power plant, forged to order by Jiangyin Jiangnan Metal Co., Ltd.
X10CrWMoVNb9-2, European material number 1.4901, is a 9 % chromium creep strength enhanced ferritic (CSEF) martensitic steel containing about 1.5 to 2.0 % tungsten and 0.3 to 0.6 % molybdenum, micro-alloyed with vanadium and niobium and with controlled nitrogen and boron. It is the European equivalent of ASME grade P92 / T92 / F92 (UNS K92460), and it is used for main steam piping, boiler headers, valves and fittings working continuously at up to about 620 °C.
Jiangyin Jiangnan Metal Co., Ltd., an open die forging factory at No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China, forges X10CrWMoVNb9-2 into round bars, seamless rolled rings, flanges, discs, blocks, hollow bars and valve components, supplied normalized and tempered (+NT) with EN 10204 3.1 or 3.2 certification. Enquiries go to sales@steelforgepieces.com or +86 189 2135 9659.
X10CrWMoVNb9-2 appears under several national designations. Chemistry and minimum mechanical requirements are essentially the same across them, and the differences lie in product form, testing scope and certification. State the governing specification on the purchase order.
| Standard or region | Designation | Product form covered |
|---|---|---|
| EN name and number | X10CrWMoVNb9-2 / 1.4901 | Tubes, forgings, bars, plate |
| EN 10216-2 | X10CrWMoVNb9-2 | Seamless tubes for pressure purposes |
| EN 10222-2 | X10CrWMoVNb9-2 | Steel forgings for pressure purposes |
| ASTM / ASME A182, A336 | Grade F92, SA-182 F92 | Forged flanges, fittings, valves, rings, discs |
| ASTM / ASME A335 | Grade P92, SA-335 P92 | Seamless ferritic alloy steel pipe |
| ASTM / ASME A213 | Grade T92, SA-213 T92 | Boiler and superheater tubes |
| ASTM A234 | Grade WP92 | Wrought piping fittings |
| UNS | K92460 | Not applicable |
| Japan, original development | NF616 | Tubes and pipe |
| China GB/T 5310 | 10Cr9MoW2VNbBN | High pressure boiler tubes |
| Welding group | ASME Section IX P-No. 15E, ISO/TR 15608 Group 6.4 | Procedure qualification |
Cross references are given for guidance. Minor differences in permitted element ranges and mandatory tests exist between EN and ASME specifications, so equivalence should be confirmed by your design authority before substitution.
The composition limits below are those of EN 10216-2 for grade X10CrWMoVNb9-2, in percent by mass, balance iron. Both ladle and product analysis are reported on every EN 10204 3.1 certificate we issue.
| Element | C | Si | Mn | P | S | Cr | Mo | W | V | Nb | N | B | Ni | Al | Ti | Zr |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| min. | 0.07 | n/a | 0.30 | n/a | n/a | 8.50 | 0.30 | 1.50 | 0.15 | 0.04 | 0.030 | 0.0010 | n/a | n/a | n/a | n/a |
| max. | 0.13 | 0.50 | 0.60 | 0.020 | 0.010 | 9.50 | 0.60 | 2.00 | 0.25 | 0.09 | 0.070 | 0.0060 | 0.40 | 0.020 | 0.010 | 0.010 |
Values apply to the normalized and tempered (+NT) delivery condition. Forgings are tested in the direction and location required by the governing specification. For heavy sections the test piece position is agreed at order stage.
| Property | Symbol | Requirement |
|---|---|---|
| Tensile strength | Rm | 620 to 850 MPa |
| 0.2 % proof strength | Rp0.2 | min. 440 MPa |
| Elongation at fracture, longitudinal | A | min. 19 % |
| Elongation at fracture, transverse | A | min. 17 % |
| Impact energy at +20 °C, longitudinal | KV | min. 40 J |
| Impact energy at +20 °C, transverse | KV | min. 27 J |
| Typical hardness as delivered | HB | about 200 to 250 HBW |
Hardness is indicative. Where a maximum hardness is imposed, for example 250 HBW for certain service conditions, state it on the order so that tempering can be set accordingly.
| Property | Value |
|---|---|
| Density at 20 °C | about 7.76 g/cm³, 7760 kg/m³ |
| Modulus of elasticity at 20 °C | about 216 GPa |
| Modulus of elasticity at 600 °C | about 150 GPa |
| Mean coefficient of thermal expansion, 20 to 600 °C | about 12.4 x 10-6 K-1 |
| Thermal conductivity at 100 °C | about 28 W/(m·K) |
| Specific heat capacity at 20 °C | about 470 J/(kg·K) |
| Electrical resistivity at 20 °C | about 0.60 µΩ·m |
| Transformation temperature Ac1 | about 800 °C, confirm by dilatometry per heat |
| Magnetic | Yes, ferromagnetic |
Creep governs the practical temperature ceiling for this grade. The ECCC 2005 re-assessment, built on a database of roughly nine million testing hours, puts the mean stress to rupture in 100 000 hours at 600 °C at about 113 MPa, falling to about 101 MPa for 200 000 hours at the same temperature. That is some 20 to 30 % above Grade 91. For ultra supercritical steam conditions this allows thinner pipe walls, lower through wall thermal stress and less weld metal for the same duty, which is why Grade 92 is specified in place of Grade 91 on modern plant.
Design note. The figures above are mean assessed values for base metal. Cross weld strength is lower, and Type IV cracking in the fine grained heat affected zone governs long term weldment life. Take allowable stresses for design from the applicable code, such as ASME BPVC Section II Part D, EN 13480 or EN 12952, and not from this page.
Creep performance of this grade depends on obtaining a fully martensitic structure after normalizing, then a uniform tempered martensite. We heat treat in computer controlled furnaces with calibrated multi zone thermocouples, and the complete time temperature chart goes out with each batch.
| Operation | Temperature | Cooling | Purpose |
|---|---|---|---|
| Forging | start 1150 to 1180 °C, finish above 900 °C | Air or controlled | Break down cast structure, close porosity |
| Normalizing, austenitizing | 1040 to 1090 °C | Air, or forced air and polymer for heavy sections | Dissolve carbides, form full martensite on cooling |
| Tempering | 730 to 780 °C, held below Ac1 | Air | Precipitate M23C6 and MX, restore toughness |
| Post weld heat treatment | 750 to 770 °C | Air, controlled rate | Temper the weld and HAZ martensite |
| Stress relief after machining | By agreement, below final tempering temperature | Furnace or air | Relieve machining stresses without over tempering |
Soaking times are commonly specified as a function of ruling section, for example one hour per 25 mm subject to a stated minimum. If Ac1 is exceeded during tempering or PWHT the material is re-austenitized and untempered martensite results, and a full re-normalize and re-temper is then required.
X10CrWMoVNb9-2 welds by SMAW, GTAW, SAW and FCAW with matching 9Cr-2W consumables. The procedure window is narrow and must be qualified.
Everything listed below is produced to order by open die forging and ring rolling at our Jiangyin works, then normalized, tempered, machined and inspected. Most of what we ship is made to customer drawing.
| Product form | Typical size range | Notes |
|---|---|---|
| Forged round bars and rods | dia. 80 to 1200 mm, length up to 6000 mm | Black, rough turned or peeled |
| Square, rectangular and flat bars | thickness 50 to 800 mm, width up to 1500 mm | Sawn or machined all over |
| Seamless rolled rings | OD 200 to 4000 mm, wall 30 to 500 mm, height up to 1000 mm | Radial axial rolled, circumferential grain flow |
| Hollow bars, sleeves, bushes, cylinders | OD 100 to 1200 mm, ID from 50 mm | Trepanned or mandrel forged |
| Discs, blocks and plates | OD up to 2500 mm, thickness 50 to 600 mm | Upset forged for through thickness properties |
| Forged flanges | up to 2500 mm OD, ASME B16.5, B16.47, EN 1092-1 or to drawing | WN, SO, BL, LJ, orifice |
| Valve components | bodies, bonnets, stems, seats, seat rings, gates, wedges | Near net shape forging available |
| Fittings | equal and lateral tees, Y-pieces, wye pieces, piggable wyes, caps, reducers | Forged from solid or from hollow |
Single piece weight and maximum dimensions depend on geometry. Send a drawing or a dimensioned sketch and we will confirm feasibility, the forging route and the machining allowance we can hold.
| Characteristic | X10CrWMoVNb9-2 (1.4901 / P92) | X10CrMoVNb9-1 (1.4903 / P91) |
|---|---|---|
| Tungsten | 1.50 to 2.00 % | Not added |
| Molybdenum | 0.30 to 0.60 % | 0.85 to 1.05 % |
| Boron | 0.0010 to 0.0060 %, controlled | Not specified |
| Tensile strength Rm | 620 to 850 MPa | min. 585 MPa |
| Proof strength Rp0.2 | min. 440 MPa | min. 415 MPa |
| Creep rupture, 600 °C / 105 h, mean | about 113 MPa | about 90 to 95 MPa |
| Typical design ceiling | about 620 °C | about 570 to 600 °C |
| Relative cost | Higher, because of the tungsten content | Lower |
| Best suited to | Ultra supercritical steam, thinner walls, reduced weld volume | Sub critical and supercritical duty where creep is less limiting |
X10CrWMoVNb9-2 is a 9 % chromium creep strength enhanced ferritic (CSEF) martensitic steel micro-alloyed with tungsten (1.5 to 2.0 %), molybdenum (0.3 to 0.6 %), vanadium and niobium, with controlled nitrogen and boron. Its European material number is 1.4901. The tungsten addition forms thermally stable M23C6 carbides and MX carbonitrides that resist coarsening, which gives it markedly higher long term creep strength than Grade 91 above 575 °C.
The EN material number, or Werkstoffnummer, is 1.4901. The corresponding UNS number is K92460.
In practice yes, they are the same grade under different standards. X10CrWMoVNb9-2 (1.4901) is the European designation. ASME and ASTM designate the same 9Cr-2W-0.5Mo-V-Nb-B-N chemistry as P92 for seamless pipe (A335), T92 for tubes (A213) and F92 for forgings (A182 and A336). There are minor differences in permitted ranges and testing, so name the governing specification on the order. We certify forgings to either designation.
Per EN 10216-2, in percent by mass: C 0.07 to 0.13, Si max 0.50, Mn 0.30 to 0.60, P max 0.020, S max 0.010, Cr 8.50 to 9.50, Mo 0.30 to 0.60, W 1.50 to 2.00, V 0.15 to 0.25, Nb 0.04 to 0.09, N 0.030 to 0.070, B 0.0010 to 0.0060, Ni max 0.40, Al max 0.020, Ti max 0.010, Zr max 0.010, balance iron.
At room temperature after normalizing and tempering: tensile strength Rm 620 to 850 MPa, 0.2 % proof strength Rp0.2 minimum 440 MPa, minimum elongation A of 19 % longitudinal and 17 % transverse, and minimum Charpy V-notch impact energy at +20 °C of 40 J longitudinal and 27 J transverse.
Continuous service is normally specified up to about 600 to 620 °C in ultra supercritical steam plant, with lightly stressed or short term use reported up to about 650 °C. Creep sets the limit rather than scaling. The ECCC 2005 assessment gives a mean 100 000 hour rupture strength of about 113 MPa at 600 °C.
Forgings are normalized at about 1040 to 1090 °C and air cooled to produce a fully martensitic structure, then tempered at about 730 to 780 °C and air cooled. Tempering must stay safely below Ac1, approximately 800 °C, so that the material is not re-austenitized. We record the full time temperature trace of every heat treatment charge and issue it with the EN 10204 3.1 certificate.
Yes, with strict procedure control. Typical practice is preheat and interpass of 200 to 300 °C, matching 9Cr-2W hydrogen controlled filler, cooling the joint to about 80 to 120 °C so that the martensite transformation completes before post weld heat treatment, then PWHT at about 750 to 770 °C held below Ac1. A qualified WPS to ASME Section IX (P-No. 15E) or ISO 15614-1 is required, and Type IV creep damage in the fine grained HAZ must be allowed for in design.
Grade 92 contains 1.5 to 2.0 % tungsten, which Grade 91 does not, together with lower molybdenum (0.3 to 0.6 % against 0.85 to 1.05 %) and a controlled boron addition. This gives substantially higher creep rupture strength above 575 °C, which allows thinner pipe walls, lower thermal stress and less weld volume for the same duty. Grade 91 stays the more economical choice below about 570 °C.
Jiangyin Jiangnan Metal Co., Ltd. is an open die forging factory at No.1 Chengxiqiao Road, Zhouzhuang Town, Jiangyin City, Jiangsu Province, China, manufacturing X10CrWMoVNb9-2 forged round bars, seamless rolled rings, flanges, discs, blocks, hollow bars, valve bodies, bonnets, stems, seat rings and forged fittings. Contact sales@steelforgepieces.com or +86 189 2135 9659 with a drawing or specification for a quotation.
Standard delivery includes an EN 10204 3.1 material test report with ladle and product analysis and room temperature mechanical results, the heat treatment time temperature chart, ultrasonic examination to EN 10228-3 or ASTM A388, magnetic particle examination, hardness survey, PMI verification and a dimensional report. EN 10204 3.2 certification with a nominated third party inspector is available on request.
Yes. Open die forging and radial axial ring rolling are our standard routes, and most of what we ship is made to customer drawing. Send a 2D drawing or a 3D model together with the governing specification, delivery condition, NDE acceptance class and certification level, and we will confirm the forging route, machining allowance, lead time and price.
This page is a commercial data sheet prepared by the engineering department of Jiangyin Jiangnan Metal Co., Ltd. Values given are typical or specification minima, and they do not replace the governing standard, the design code or the mill test certificate for your specific order. Last technical review: .
Send a drawing or your specification and we will reply with a firm price and lead time. Please include the grade and standard, the product form and dimensions, quantity, delivery condition, NDE acceptance class and the certification level you require.